United States Patent [9191
[111
Saito
[451 Jan. 22, 1974
[54] LAMINATED‘ IRON CORE OF ROTARY
ELECTRIC MACHINES
[75] Inventor: Kiyoshi Saito, Hitachi, Japan
[73]’ Assignee: Hitachi, Ltd., Tokyo, Japan
[22] Filed:
July 11, 1972
[21] Appl. No.: 270,871
[52]
[51]
[58]
such that one radial marginal periphery de?nes a half
of a coil slot and the opposite periphery de?nes a half r,
of a tooth between the two coil slots.
Accordingly, when such segments are juxtaposed to
310/259
,
[57]
ABSTRACT
A newly developed laminated iron core is composed
of number of unit segments, each of which is shaped
form a layer of an annular iron core, a pair of the
segments constitute a sector having an odd number
US. Cl. ............................... .. 310/217, 310/258
Int. Cl. ........................................... .. H02k l/06
Field of Search .................. .. 310/216-218, 258,
[56]
3,787,744
(2n + l) of coil slots, wherein n is the number of coil
slots in a unit} segment, whereas a pair of unit
segments of ordinary type bears an even number of
coil slots.
Assembled iron cores each using either one of the
References Cited
type mentioned above bear a different number of coil
UNITED STATES PATENTS
slots suitable for different frequencies such as 50
3,652,889
3/1972
Reece et a1, .................. .. 310/217 X
3,488,754
l/1970
Hohnstein . . . . . . . . .
. . . . . ..
310/216
3,307,059
2/1967
Kitano et al. . . . . .
. . . . . .. 310/216
1,779,950
10/1930
Reichel . . . . . . . . . . . . .
. . . . . ..
310/258
2,774,000
12/1956
Ross . . . . . . . . . . . . . .
. . . . . . . . . ..
310/216
3,221,195
11/1965
Hoffman ....................... .. 310/217 X
Primary Examiner-J. D. Miller
Assistant Examiner-—M_a_rk O. Budd
Arviofhey, Agemrtt, or Firni-lFaul M. Craig, Jr‘. ‘et a1.
Hertz and 60 Hertz but has the same outside and
inside diameter and the same number of dovetail
notches, thereby permitting two kinds of iron cores to
be supported within a stator frame of single uni?ed
type.
7 Claims, 4 Drawing Figures
3.787. 744v
PATENTEI] JAN 22 IBM
SHEET 1 OF 3
F/GT/I
3,787,744
1
LAMINATED IRON CORE OF ROTARY ELECTRIC
MACHINES
‘
'
This invention relates to improvements in laminated
iron cores used in rotary electric machines, such as
tary electric machines is changed from 30 to 36, 42, 48,
54, 60, 66, 72, 78 by the number of 6, and on the other
hand, the number of segments is an integer into which
all the slots are completely divided, as the segment iron
plate is divided euqally as has been stated previously.
In view of the foregoing, the relation between the
number of segments and the number of key bars sup
porting the iron core, for each number of slots in the
large capacity turbine generators or water-wheel gener
ators, and more particularly to improvements in such
laminated iron cores in which unit segments constitut
ing the iron core are juxtaposed side by side and are
stacked one after another in such a manner that the
segments juxtaposed in a flat plane form a unit layer of
an iron core and the stacked segments constitute multi
conventional stator cores is summarized as follows:
ple unit layers laminated in a staggeredrelation to each
other-so that one layer has a lead having a pitch of one
coil slot with respect to the nextlayer and so on, pro
gressively.
'
2
be changed and accordingly causes the stator frame to
be changed as will be described in detail later.
In the past, it has been usual that the number of coil
slots of a stator core used in large-sized, high speed, ro
Total
.
In general, a stator core used in large capacity rotary
electric machine is composed of a plurality of iron
plates laminated one after another each consisting of a
Number
Number
number of slots
of segments
of key bars
30
36
42
48
l0, l5
l2, 18
14, 21
l2,l6, 24
l0, 15
12, 18
I4, 21
12,16,24
54
18
l
20 60
66
silicon steel having a thickness of about 0.35 mm, one
72
or both surfaces thereof is applied with insulating treat
78
ment in order to prevent a loss caused by eddy current
>
15, 20
I5, 20
22
18, 24
18, 24
26
From the above table, it will be apparent that a change
.
By reason of increasing the available percentage of 25 in the total number of slots results in a change in the
number of segments and the number of key bars,
the blank‘ sheet materiaLand magnetic orientation, it
namely, the stator frame is to be changed, since the key
becomes necessary to make these iron plates from the
bars are kept integral with the stator frame.
blank sheet material in such a manner that the mag
More practically, in case, for example, of machines,
netic resistance of the product core will become small
during the rotation of the core.
est, and to this end'it is a common practice to divide
such as a standard gas turbine generator, the stator of
each'iron plate circumferentially into a plurality of seg
which is produced by mass production with the same
diameter, only a change in the total number of slots,
caused by a partial change in the requirement, e.g., a
difference of frequency between 50 Hertz and 60
ments, i.e., sectoral segments.
In this case, if thesegments of the iron plate are dif
ferent in size from each other, a corresponding number
of different dies will be required for punching these 35 Hertz, or a difference of terminal voltage, causes the
stator frame to be further changed due to the differ
segments out of the'blank sheet material, which is very
ence of the number of key bars, even though the outer
uneconomical. Therefore, it is usual to divide'the iron
diameter and thickness of the iron core remain the
plate equally in the circumferential direction into a plu
rality of segments.
same.
’
The iron plates, i.e., segment iron plates, each being
40
divided as above described, are juxtaposed side by side
and stacked one on another so as to be laminated in
staggered relation to each other to form an annular iron core, but the iron core of such a construction has a
number of problems yet to be solved.
For instance, the manner of staggering the segment
iron plates relative to each other, the method of sup
porting the thus laminated iron core on the stator
frame, the relation between the supporting members
and each of the iron plates, and the relation between
45
This means that in the mass production, for example,
of rotary electric machines for use with 50 Hertz and
60 Hertz, a stator frame for 36 slots and 12 key bars,
and a stator frame for 42 slots and 14 key bars must be
provided separately to each other, which is undesirable
from the standpoint of mass production and has ad
versely affected shortening of the delivery term and re
duction of the production costs of the rotary electric
machines.
As may be apparent from the foregoing description,
again with reference to the above-described case, it
would be very advantageous from the standpoint of
the number of divisions of the iron plate and the num
bers of the supporting grooves and coil slots, are such
mass production if the two types of cores having 36
slots and 42 slots could be supported by a uni?ed type
problems.
stator frame for 12 segments and l2 key bars because
The present invention is intended to solve these prob
only one stator frame will suffice the need.
55
lems.
In this view, the object of the present invention is to
In the production, for example, of a generator which >
provide a laminated iron core of the type described,
has a predetermined capacity at a predeterminedout
which enables the same stator frame to be used without
put voltage, it would be certainly idea] if a generator of
the same capacity at the sanie voltage can be obtained
only by changing the rotational speed, even if there is
a frequency difference between 50 Hertz and 60 Hertz.
In general, however, the output voltage necessarily var
ies when the rotational speed changes, and hence it is
the necessity for changing the number of key bars, even
when the number of coil slots slightly changes, and
which, therefore, is desirable from the standpoint of
mass production of rotary electric machines compris
ing such an iron core.
In order to attain the object set forth above, accord
a usual practice to change the number of turns of the 65 ing to the present invention there is provided a lami-i
nated iron core of rotary electric machines, in which
coil according to the frequency.
-
Changing the number of turns of the coil, therefore,
each segment iron plate constituting the laminated iron
causes the number of the coil slots of the iron core to
core is prepared as a sector and each of said segments
3,787,744
3
4
is so shaped that one radial circumferential side thereof
Each annular iron disc is composed of a plurality of
unit segments 11 each being of the shape as shown in
de?nes the half of the coil slot, while the other circum
FIG. 2.
As shown in FIG. 2, each segment 11 has dovetail
notches 9 formed in the outer peripheral edge thereof
as stated previously for receiving the key bar 7 of the
stator frame 1 and has coil slots 12 formed in the inner
peripheral edge thereof for receiving a coil.
2
ferential side thereof de?nes the half of the tooth
formed between the adjacent coil slots.
According to another aspect of the invention there is
provided a laminated iron core of the character de
scribed above, in which each segment iron plate is
formed along the outer peripheral edge thereof with
As shown, the segment 11 has a sectoral shape and
supporting notches, the number of which is a multiple
of the number of the coil slots provided along the inner
peripheral edge. -
is formed with the coil slots 12 and dovetail notches 9,
and in more detail, is shaped as will be described below:
Namely, as shown in FIG. 2, the segment is so shaped
that the center'of the coil slot 12 is located at one cir
cumferential end a thereof or, in other words, said cir
cumferential end a will de?ne the half of the coil slot,
-
As a result, a plurality of segments constitute an an
nular disc of single layer, when they are juxtaposed side
by side in a plane, also a pair of the juxtaposed seg
ments constitute a sector having an odd number of coil
slots represented by 2n + I, wherein n is the number of
and the center of the tooth is located at the other cir
cumferential end b thereof.
coil slots in a single segment.
'
In an embodiment as shown in FIG. 3, two different
types 11a and 11b of such segments 11 are provided,
which are different from each other in respect of the
positions of the dovetail notches as shown in FIG. 3 and
Also the segments are stacked one piece on another
to form a great number of layers to constitute a lami
nated iron core, further in stacking, each segment is po
sitionecl in a staggered relation to keep a lead of a pitch
of one coil slot with respect to the one immediately be
these two segments 11a, 11b are arranged side by side,
with the halves of coil slots at one of the ends thereof
low.
'
joined together and the halves of teeth at the other ends
All of the segments thus assembled have both coil 25 thereof joined together,‘ to form one segment plate. The
slots and key bar notches each vkept in alignment
throughout the whole laminated layers and maybe se
segments are also stacked one on another with the
joints of one unit segment being staggered from the
cured by at least one key bar and at any one of its full
key slots.
other immediately below in a similar manner, as shown
‘
in FIG. 4 (No. 1, No.2 and No. 3 in FIG. 4 indicate the
And further each segment is composed of a plurality 30 staggered state) of another embodiment.
of segments which are so shaped that only one punch
In this case, the respective segment plates are each
ing die will suffice the punching of them from a blank
supported by at least one key bar 7 at the full dovetail
sheet material.
FIG. 1 is a perspective view, partially broken away,
notch formed in the outer peripheral edge thereof as a
matter of course and thus the entire core is supported
of a stator comprising the laminated iron core of the 35 in the stator frame 1.
present invention;
. ’
Now, the reason why the stator core of the construc
FIG. 2v_i_s a perspective view of the unit segment con
tion described above can be supported by stator frames
stituting the segment iron plate of the laminated iron
having the same number of key bars even if the total
core shown in FIG. 1; and
number of coil slots are slightly different, will be de
FIGS. 3 and 4 are plan views respectively illustrating 40 scribed using practical numerical values. With refer
the different manners of putting the unit segments to
gether.
ence, for example, to a stator with 36 slots, 12 segments
and 12 key bars and a different stator with 42 slots, 12
The present invention will be described in detail
hereunder with reference to the embodiment shown in
segments and 12 key bars, which have conventionally
the drawings.
45
'
Referring first to FIG. 1 there is shown in partially
broken away perspective view the essential portion of
selectively been used with a current frequency of 50
Hertz and of 60 Hertz, respectively, if each segment
plate of the core of the former stator is composed of 12
segments each having three coil slots arranged symmet
a stator for use in turbine generators, which comprises
rically with those of the adjacent segment, the iron core
a stator frame 1 and a stator core 2.
will have a total of 36 slots as will be obvious from 3 X
secured to said main plates 3, 4. Axially extending key
stator core in a stator frame having 12 key bars.
The stator frame 1 is composed of hollow, substan 50 12 = 36 and hence the stator core will have 36 coil
tially circular ‘main plates 3, 4 and a cylindrical plate 6
slots, so that there will be no problem in mounting the
In the latter stator, the segment plate of the stator
bars 7 are ?xed to the inner peripheral edges of the
core is composed of segments 11a and 11b of the type
main plates 3, 4 in the circumferential direction of said
main plates at a predetermined interval between each 55 shown in FIG. 3 as described previously and each seg
ment is provided with 3.5 notches, and such segments
other.
are juxtaposed side by side and stacked one on another
in staggered relation in such a manner that the halves
These key bars 7 serve'to hold the stator core 2 dis
posed within the stator frame 1 and each has a dovetail
key 10 along the inner surface thereof.
The dovetail 10 may be formed integrally with the
key bar 7 by cutting or may be fabricated separately
from the key bar 7 and secured to said key bar by weld
ing or with bolts or like means.
60
the assembled state of the stator, is annular in shape
and is composed of a plurality of annular discs each
‘consisting of segments juxtaposed side by side.
coil slots as described previously.
Namely, the core will havea total of 42 coil slots as
will be obvious from 3.5 X 12 (the number of seg
ments) = 42 and can be mounted in the stator frame
4
‘The stator core‘2 supported by these key bars 7, in
of the slot are joined together to form axially alligned
65
having 12 key bars.
As described, even the core of the type having, for
example, 42 slots can be mounted in the stator frame
having 12 key bars, if said core is constructed accord
3,787,744
5.
.
as intended for a core having 36 slots can be used for
such a core.
6
chine, comprising, a plurality of unit segment plates dis
posed side by side to form annular layers laminated one
on another axially with the joint of each segment plate
ing to the present invention, and the same stator frame
'
in staggered relation to the joints of the other segment
Hereinbefore, it has been stated that two different
types of segments 11a and 11b are prepared for the
plates into a core of an annular shape, each of said seg
ment plates being provided with supporting notches in
purposes of minimizing the number of the dovetail
notches formed in the outer peripheral edge of the seg
ment iron plate. However, only one type of segment
the outer peripheral edge and coil slots in the inner pe
ripheral edge thereof, one radial marginal side of each
segment plate de?ning one-half of a coil slot and the
opposite side thereof de?ning one-half of a tooth
will suffice the need when the number of the dovetail
notches is selected as will be described below:
FIG. 4 indicates another embodiment of the inven
tion, in which the number of the dovetail notches is se
lected such that it is always two-fold of the number of
formed by the adjacent coil slots, whereby each seg
ment plate may be supported by at least one key bar at
a supporting notch.
the coil slots and the segment iron plates each having
2. A laminated iron core for a rotary electric machine
as claimed in claim 1, wherein the number of said sup
porting notches provided in said annular core is a mul
such a number of dovetail notches are juxtaposed side
by side and front side front and back side front alter
tiple of the number of the coil slots.
nately and also stacked one on another in staggered re
lation.
In this way, only one type of segment 110 will suf?ce
the need and hence only one type of punching die is re
of l2(n + 0.5) coils is supported by a stator frame hav
quired for the fabrication of segment iron plates so that
ing 12 key bars.
3. A laminated iron core for a rotary electric machine
as claimed in claim 1, wherein said core having a total
4. A laminated iron core as claimed in claim 1,
the cost of punching die is reduced and in addition, uni
wherein a plurality of annular layers composed of said
fied segments of one type can be easily prepared, with
segment plates and having a total of 42 coil slots are
out paying any particular attention to the number of
segments of each type to be produced.
25 supported by a stator frame having 12 keybars.
Although the foregoing description has been given by
5. A laminated iron core for a rotary electric machine
using speci?c numerical values, it will be understood
that in general stator segment plates each having a total
as claimed in claim 2, wherein alternate segment plates
are disposed upside down so that said half coil slot and
said half tooth of adjacent segment plates are reversed
of l2n slots and l2(n + 0.5) slots (wherein n is an inte
ger) can be assembled and received within a stator
frame having 12 key bars.
to combine with the half coil slot and half tooth of the
adjoining segment plate.
'
6. A laminated iron core for a rotary electric machine
as claimed in claim 5, wherein said core having a total
of l2(n + 0.5) coils is supported by a stator frame hav
According to the present invention, as described
herein, laminated cores of the type described, which
enable the same stator frame to be used, without
changing the number of key bars even if the number of 35 ing 12 key bars.
7. A laminated iron core as claimed in claim 5,
coil slots is slightly varied, and hence is desirable from
wherein a plurality of annular layers composed of said
the standpoint of mass production of stator cores for
segment plates and having a total of 42 coil slots are
rotary electric machines.
supported by a stator frame having 12 key bars.
I claim:
*
1. A laminated iron core for a rotary electric ma
45
50
55
60
65
*
*
*
*